Wafer quality analysis of various scribe line mark designs

Scribe Line Marks (SLM) printed on substrates are a standard method used by modern scanners for wafer alignment. Light reflected from the SLM forms a diffraction pattern which is used to determine the exact position of the wafer. The signal strength of the diffraction order needs to reach a certain threshold for the scanner to detect it. The marks are changed as the wafers go through various processes and are buried underneath complex film stacks. These processes and stacks can severely reduce wafer quality (WQ). Equipment manufactures recommend several variations of the SLM to improve WQ but these variations are not effective for certain advanced processes. This paper discusses theoretical analysis of how SLM designs affect wafer quality, addresses the challenge of self-aligned double patterning (SADP) on SLMs and experimentally verifies results using various structures.